Yup, blew my mind when I discovered it 20+ years ago. Note also that quite a few Apple ][ disk copy protections invented their own pcode like language to obfus

Yup, blew my mind when I discovered it 20+ years ago. Note also that quite a few Apple ][ disk copy protections invented their own pcode like language to obfuscate their protection. They had something like 10-15 opcodes to do basic operations such as read/write tracks, registers or stacks, etc...